Formatting your external: Plug in your external drive and back up anything that's already on it.A bit of time! This took about four hours of processing for my 160gb drive on a 1.83ghz Core Duo Macbok.A blank external FireWire hard drive, size equal or larger than your current drive.So, here's how I went from an Apple Partition Mapped drive to a GUID drive for Leopard, without losing any of my data, settings, or having to re-install my applications. I read a couple guides online, and they involved simply copying your user folder and reformatting the drive, but I wanted a method that copied absolutely everything so that I wouldn't have to install my horde of apps. My Intel Macbook still booted from this drive, but having my hard drive in Apple Partition Map mode had two severe drawbacks: The normal partition type for a Intel Mac boot drive is GUID. While upgrading the laptop hard drive on my Macbook, I inadvertantly partitioned the new hard drive in the 'Apple Partition Map' mode, which is reserved for PowerPCs.
